BIO152 WK6 Lecture Notes

BIO152 WEEK 6

Prokaryotic Growth and Metaboois m

- Prokaryote are sngie ceiied mscroboe
- The ceii tructure s smpier than that of eukaryotic organs m a there s no nucieu
or memborane boound organeiie
- Thesr controi centre contasnsng the genetic snformation s contasned sn a sngie ioop
of DNA
- Some boactersa have extra chromo omai DNA caiied pia msd
- Ssmpie unsceiiuiar organs m wsth ome dsference sn tructure to euakaryotic ceii
- Prokaryote : no nucieu , no organeiie , bosnary f son, maiier 3 RNA rsboo ome
- Eukaryote : ha a nucieu , ha organeiie , msto s and meso s , iarger 4 RNA
rsboo ome
- Some boactersa can grow on a dsver sty of compound e.g. aromatic and heterocycisc
hydrocarboon , antibosotic , pe ticsde and herboscsde , detergent

Requsrement for boactersai growth
- Energy
- Carboon
- Nstrogen
- E entiai macronutrsent – S, P, Ca, Mg etc
- E entiai mscronutrsent – Cu, Mn, nn, Mo etc
- Growth factor – vstamsn , amsno acsd

What type of metaboois m occur on boactersa?
- Aii type !
- Photoautotroph ( unisght, CO2)
- Chemoautotroph (snorgansc chemscai , CO2)
- Photoheterotroph ( unisght, organsc compound )
- Chemoheterotroph (organsc compound , organsc compound )
- Bactersa and eukaryote u e smsiar metabooisc pathway to obotasn energy bout have a
dsferent ceiiuiar tructure
- In eukaryote the eiectron tran port chasn s iocated sn the mstochondrsa
- In prokaryote the eiectron tran port chasn s iocated sn the ceii pia ma memborane

Bactersai ceii growth and dsvs son
- Bactersa reproduce boy bosnary f son
- The sngie boactersai ceii dsvsde snto two sdenticai daughter ceii
- Growth of boactersai popuiation s exponentiai
- 1  2  4  8  16  32 etc
- If we piot the numboer of boactersai ceii ver u time on isnear graph paper, the isne
how an exponentiai sncrea e
- But sf we convert to the verticai axs to a iogarsthmsc caie, we wsii fnd that a teady
rate of growth s a trasght isne
- Bactersa do not continue to grow wsthout ismst
- 4 pha e of growth

, Pha e 1: Lag Pha e
- Ceii are aisve bout popuiation s not sncrea sng, ceii are not douboisng
- Persod of adju tment to new condstion , may boe a change sn carboon ource, temp or
pH
Pha e 2: Exponentiai Pha e
- Ceii are growsng and dsvsdsng at a con tant rate
- The rate of boactersai growth can boe mea ured
- It s dursng the exponentiai pha e that the growth rate s mea ured
- Mean Generation Tsme (MGT) s the time requsred for one generation or dsvs son of
boactersa
- MGT s the time taken for the popuiation to douboie
- MGT depend on pecse of boactersa, type of growth medsum and envsronmentai
condstion e.g. pH, temp, aeration
- MGT varse for dsferent pecse of boactersa
- E.g. E.cois = 15 msnute , ome osi boactersa = 300 hour , boacsiiu app = 30 msn
- Bactersa need 40 msn to repiscate DNA
Pha e 3: Stationary Pha e
- Popuiation top sncrea sng
- Growth top boecau e of envsronmentai change due to; nutrsent depietion, pH
change, iack of oxygen and toxsc compound
Pha e 4: Death/Decisne Pha e
- Ceii dse boecau e of; nutrsent depietion, pH change, iack of oxygen, toxsc compound

How can we mea ure boactersai growth?
- A boactersa grow over time, we mea ure an sncrea e sn:
- Turbosdsty – abo orboance at 600nm
- Dry wesght of ceii
- Count of vsaboie ceii
- Dsrect ceii count
- Protesn mea urement

Envsronmentai factor
- Have an efect on the urvsvai and growth of boactersa:
- Water
- Temperature
- pH
- oxygen
Water
- isqusd water s requsred for ceii metaboois m
- the pre ence of avasiaboie isqusd water s e entiai for boactersa to grow
- water can boe pre ent sn an envsronment bout not avasiaboie to boactersa
- the avasiabosisty of water s determsned boy amount and type of oiute ds oived sn
the water
- Common oiute on water are:
- Inorgansc compound e.g. Na+Ci- or K+, Mg++
- Organsc compound e.g. ugar, amsno acsd , organsc acsd